an interesting spectrum - any ideas ?

[Mike in MD]

Hi. For those of you who aren't bored with looking at the frequency content of music downloads, maybe you have some ideas on what is happening to the recordings below. I considered that the microphone might be at a null-point of a standing wave, but I would expect frequencies ratios of 1,3,5,7, etc. But this looks like 1,2,3,4,5.

 

Anyway, this is: Chesky, Jimmy Cobb, Cobb's Corner. I looked at WAV files with Audacity and Sonic V. Here is Ruby My Dear on Audacity

 

 

And here is I May Be Wrong.

 

 

They both show *suck-out* bands. It is even more clear in Sonic V on Ruby My Dear.

 

 

I used Sonic V to estimate the frequencies of the centers of the suck-outs. I got 6500, 12500, 18500, 25000, 31500 and 37600. There was a final cut-off at about 44300.

 

I have no idea what could cause this on one channel. Maybe one of the experts here can explain it.

 

Mike

 

 

[Miska]

I used Sonic V to estimate the frequencies of the centers of the suck-outs. I got 6500, 12500, 18500, 25000, 31500 and 37600. There was a final cut-off at about 44300.

 

6500 Hz is quite close distance... Reflection from Jecklin disk?